Update `Restarter` to be much more defensive when attempting to clear
caches. We now use `clearCache()` methods whenever possible, and only
fall back to field access when absolutely necessary. In addition field
access now ignore any exceptions.

Fixes gh-12719

See gh-12695

See gh-12692

Closes gh-12526

* pr/12629:
  Polish "Use secure connection to repositories"
  Use secure connection to repositories

Closes gh-12629

See gh-12629

Closes gh-12636

* pr/12535:
  Fix ModifiedClassPathRunner tests if run via IDEA

IntelliJ can shorten the classpath to a single classpath.jar in order to
circumvent errors originating from a too long classpath. This breaks the
filtering inside ModifiedClassPathRunner as the classpath contains only a
single jar to match against. This can be fixed by applying a similar
mechanism already provided for Surefire manifest-only booter JARs, which
extracts the real classpath from the JAR's Manifest file.

See gh-12535

Closes gh-12614

Closes gh-12613

Closes gh-12573

* gh-12554:
  Polish "Use this.out in SummaryProgressReporter.finished()"
  Use this.out in SummaryProgressReporter.finished()

See gh-12554

Closes gh-12554

Refine `BasicErrorController` mappings so that only JSON and XML get
structured responses. A simple string response is returned for all
other media types.

Fixes gh-12513

Update JAR `Handler` logic so that the existing `jarFile` is only used
if the requested URL starts with the same path. Prior to this commit it
was possible to construct a URL with another URL as context. This could
mean that the `handler` was shared and the already resolved `jarFile`
contained in the handler wasn't necessarily suitable.

Fixes gh-12483

Closes gh-12393

Closes gh-12498

Closes gh-12497

Closes gh-12496

* pr/12422:
  Polish

Closes gh-12422

Closes gh-12434

Closes gh-12409

Uses snapshots of the Dependency Management Plugin causes problems as
they are only published to our plugins-snapshot repository which may
not be configured in someone's build.

See gh-12406

See gh-12406

Closes gh-12402

Closes gh-12386

Closes gh-12385

Closes gh-12384

Closes gh-12383

Closes gh-11475

See gh-12365

This commit fixes a NPE when the static-locations array of
`ResourceProperties` has to be expanded as the setter is cleaning the
values of the array and is affected by a non-intuitive behaviour of the
binder.

When the binder needs to set an element of an array and the size of the
array isn't large enough, the binder proceeds as follows:

* An array of the required size is created
* The content of the original array is copied over
* The setter of the property is invoked with the new array
* The setter of the property is invoked and the returned array is
mutated to set the requested value

While one would expect the array to contain the requested value when the
setter is invoked, this is not the case. Also, the array might contain
null values if a value at index 8 should be set and the array has a size
of 3.

All in all, `ResourceProperties#appendSlashIfNecessary` has to account
for `null` and an additional round of cleaning has to happen once
binding has completed.

Closes gh-12360

Closes gh-12299

See gh-12344